A vehicle surroundings monitoring device has been proposed that binarizes, based on a predetermined brightness threshold value, the data of images (gray scale images) of the surroundings of a vehicle which are captured by an infrared camera mounted on the vehicle, and extracts the image of a living body (such as a pedestrian, or an animal) which has a brightness greater than or equal to the brightness threshold value (for example, see Japanese Unexamined Patent Application Publication No. 2007-310705).
The vehicle surroundings monitoring device described in Japanese Unexamined Patent Application Publication No. 2007-310705 determines that a real space object corresponding to an extracted image is an animal (for example, a large animal such as a deer) when the extracted binary image includes a first elliptical object area corresponding to the body of the animal, and a plurality of second object areas which are located below the first object area and smaller than the first object area.